1. Technical Field of the Invention
The present invention relates to the processing of digital images, in particular the post-processing of digital images having been compressed by means of a compression standard requiring the division of the image into several blocks, such as for example the MPEG standard.
The invention can be advantageously applied to, but is not limited to, digital video applications using large-area screens, such as plasma screens.
2. Description of Related Art
In order to transmit or to store digital images for digital video applications, the image must be compressed by means of a compression standard. In order to facilitate the compression phase, the source of pixels is converted into coefficients by means of a transformation algorithm, such as for example the Discrete Cosine Transform (DCT) conventionally used in blocks of dimension 8*8. In order that the transmission or the storage of the image be optimal, the compression ratios can be very high, which leads to compression artifacts that are hardly visible on standard resolution screens, but that are significant on large-area and high-resolution screens.
Visually, the compression artifacts appear as an edge effect associated with the blocks generated during the transformation phase, together with the presence of noise generated by transient oscillations referred to as “ringing” or “mosquito noise.”
In addition, without suitable processing to reduce these artifacts, the use of normal decoders leads to the loss of fidelity in some colors.
A need accordingly exists to provide a solution to these problems.